<PAGE>
MAS Funds
Supplement dated February 26, 1999 to the MAS Funds Adviser Class Prospectus
dated January 31, 1999
This supplement provides new and additional information beyond that contained in
the Adviser Class Prospectus and should be read in conjunction with the Adviser
Class Prospectus.
- -------------------------------------------------------------------------------
The table showing the Fees and Expenses of the Portfolios in the Adviser Class
Prospectus dated January 31, 1999 incorrectly overstates the "Other Expenses" of
the Equity and Mid Cap Value Portfolios. As a result, the "Total Annual Fund
Operating Expenses" and the "Example" table for these two Portfolios are also
overstated. The following tables correctly show the Fees and Expenses and the
Example for both the Equity and Mid Cap Value Portfolios.
FEES AND EXPENSES OF THE PORTFOLIOS
- -------------------------------------------------------------------------------
TOTAL ANNUAL
FUND
MANAGEMENT DISTRIBUTION OTHER OPERATING
FEES (12B-1) FEES EXPENSES EXPENSES
- -------------------------------------------------------------------------------
Equity Portfolio .500% 0.25% .110%* .860%
- -------------------------------------------------------------------------------
Mid Cap Value .750% 0.25% .154%* 1.154%
Portfolio
- -------------------------------------------------------------------------------
* Other expenses are based on estimated amounts for the current year.
EXAMPLE
- -------------------------------------------------------------------------------
1 Year 3 Years 5 Years 10 Years
- -------------------------------------------------------------------------------
Equity Portfolio $ 88 $274 $477 $1,061
- -------------------------------------------------------------------------------
Mid Cap Value $118 $367 $635 $1,402
Portfolio
- -------------------------------------------------------------------------------
PLEASE RETAIN FOR FUTURE REFERENCE